package com.carryduck.token;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTCreationException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.Claim;
import com.auth0.jwt.interfaces.DecodedJWT;

import java.io.UnsupportedEncodingException;
import java.util.*;

public class JwtHelper {
	// 秘钥
	static final String SECRET = "X-EB-Token";
	// 签名是有谁生成
	static final String ISSUSER = "Service";
	// 签名的主题
	static final String SUBJECT = "this is Mobile eb.common.token";
	// 签名的观众
	static final String AUDIENCE = "APP";


	/**
	 * 生成token
	 * @param userId 用户id
	 * @return
	 */
	public static String createToken(String userId){
		try {
			// 过期时间：30天
			Date expireDate = getAfterDate(new Date(),0,0,30,0,0,0);
		    return createToken(userId,expireDate);
		} catch (Exception exception){
			exception.printStackTrace();
		}
		return null;
	}

	/**
	 * 生成token
	 * @param userId 用户id
	 * @param expireDate token超时时间，单位：天
	 * @return
	 */
	public static String createToken(String userId,Date expireDate){
		try {
			Algorithm algorithm = Algorithm.HMAC256(SECRET);
			Map<String, Object> map = new HashMap<String, Object>();
			map.put("alg", "HS256");
			map.put("typ", "JWT");
			String token = JWT.create()
					// 设置头部信息 Header
					.withHeader(map)
					// 设置 载荷 Payload
					.withClaim("userId", userId)
					.withIssuer(ISSUSER)
					.withSubject(SUBJECT)
					.withAudience(AUDIENCE)
					// 生成签名的时间
					.withIssuedAt(new Date())
					// 签名过期的时间
					.withExpiresAt(expireDate)
					// 签名 Signature
					.sign(algorithm);
			return token;
		} catch (JWTCreationException exception){
			exception.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	public static String verifyTokenAndGetUserId(String token) {
		return explainToken(token);
	}

	/**
	 * 解析token
	 * @param token token
	 * @return
	 */
	public static String explainToken(String token) {
		try {
			Algorithm algorithm = Algorithm.HMAC256(SECRET);
			JWTVerifier verifier = JWT.require(algorithm)
					.withIssuer(ISSUSER)
					.build();
			DecodedJWT jwt = verifier.verify(token);
			Map<String, Claim> claims = jwt.getClaims();
			Claim claim = claims.get("userId");
			return claim.asString();
		} catch (Exception e){
			e.printStackTrace();
		}
		return null;
	}
	
	public static Date getAfterDate(Date date, int year, int month, int day, int hour, int minute, int second){
		if(date == null){
			date = new Date();
		}
		
		Calendar cal = new GregorianCalendar();
		
		cal.setTime(date);
		if(year != 0){
			cal.add(Calendar.YEAR, year);
		}
		if(month != 0){
			cal.add(Calendar.MONTH, month);
		}
		if(day != 0){
			cal.add(Calendar.DATE, day);
		}
		if(hour != 0){
			cal.add(Calendar.HOUR_OF_DAY, hour);
		}
		if(minute != 0){
			cal.add(Calendar.MINUTE, minute);
		}
		if(second != 0){
			cal.add(Calendar.SECOND, second);
		}
		return cal.getTime();
	}
	
}
